1. Field of the Invention
The present invention is related to the field of methods and apparatus for maintaining a consistent file system and for creating read-only copies of the file system.
2. Background Art
All file systems must maintain consistency in spite of system failure. A number of different consistency techniques have been used in the prior art for this purpose.
One of the most difficult and time consuming issues in managing any file server is making backups of file data. Traditional solutions have been to copy the data to tape or other off-line media. With some file systems, the file server must be taken off-line during the backup process in order to ensure that the backup is completely consistent. A recent advance in backup is the ability to quickly "clone" (i.e., a prior art method for creating a read-only copy of the file system on disk) a file system, and perform a backup from the clone instead of from the active file system. With this type of file system, it allows the file server to remain on-line during the backup.